Abstract: Advances in antiretroviral therapy have led to dramatic increases in survival of perinatally HIV- infected children into adulthood. The transition to adult HIV care, however, is replete with challenges due to the increased responsibility placed on adolescents as they enter adulthood, as well as other complex, potentially HIV-related concerns such as cognitive de?cits, depression, and stigma. Guidelines to support clinics in developing formal transition plans have been published. Nonetheless, approaches to transition vary widely across the US. Understanding the factors that impact the ability to move to adult care is critical to supporting HIV-infected youth as they transition and, hence, retaining them in care. To accomplish this, and to maintain their interest in long-term research, we must consider research methods that accommodate the lifestyles of young adults while maintaining valid data collection. Few empirical studies have systematically assessed the efficacy of current HIV healthcare transition practices, especially with regards to clinically important outcomes. Existing literature is largely qualitative, providing insights into the barriers and concerns that patients, caregivers and providers perceive as salient. This study will expand upon this research to explore the barriers and facilitators that directly affect objective clinical outcomes so as to determine which practices are effective and should be disseminated more widely. Specifically, we will determine whether individual level?factors such as age at transition, ability to manage health care, and participant involvement in transition decisions, and clinic-level structures and practices, including co- located psychological support services, written transition plans, adult care delivery models, and early presence of a transition liaison/case manager are associated with long-term retention in adult health care and viral load suppression post-transition. Subject recruitment through surveillance data and web-based data collection strategies will be evaluated to determine the feasibility of these methods as an alternative to time- and resource-intensive clinic-based research studies.